Water SA

Critical reflections on existing lawful water uses (ELUs) in South African water law

Germarie Viljoen — 2024-11-04

The National Water Act 36 of 1998 (NWA) introduced a new water law framework for South Africa. According to the NWA, all water uses must be authorised in terms of a water use licence, unless the water use constitutes a Schedule 1 water use, falls under a general authorisation, the need for a licence is dispensed with, or is recognised as an ‘existing lawful water use’ (ELU). This paper provides a critical analysis of the ELU concept within the context of South African water law. It explores the complexities and challenges associated with ELUs, including their validation, verification and registration, and also reviews recent case law that has helped to elucidate certain key aspects of ELUs. The paper underscores the necessity for more specific legislation to address these ambiguities and uncertainties. Additionally, it critically assesses the potential implications of the recently published National Water Resource Strategy III and the National Water Amendment Bill of 2023. This Bill proposes to abolish the right to declare an ELU, and to empower the relevant authority to impose conditions and/or obligations on ELUs as well as to curtail current ELU volumes.

Forecasting extreme hourly rainfall in South Africa for disaster risk reduction: thresholds and return periods

Jan H. Vermeulen — 2024-11-04

Highest and percentile values determined for daily, hourly and 5-min rainfall data (July 1994 to June 2021) from 64 automatic weather stations across South Africa were used to define extreme hourly and 5-min rainfall intensity. Internationally, 99.9th and 99.99th percentiles are typically considered as thresholds for hourly and sub-hourly extreme rainfall when forecasting for disaster risk reduction assessments. In South Africa (SA), the average of the 99.9th percentile for hourly rainfall values is 29.9 mm/h. This represents a good indicator of extreme hourly rainfall in SA and is a useful threshold for forecasting flash floods. The average highest of the hourly rainfalls for SA, 53.9 mm/h, should be a good indicator of more extreme hourly rainfalls for the country. The average of the 99.99th percentile for 5-min rainfall values is 12.8 mm/5 min, which equates to 2.6 mm/min. Significantly, the 5-min rainfall data is used to establish South African categories based on rainfall intensity and total rainfall, whereby an event can be classified as a cloudburst, downpour or shower. Using the newly established local categories, the severe thunderstorm of 4 April 2000 at Hoedspruit that produced 132.2 mm in 25 min from an intensifying upper air trough system was classified as a cloudburst. Interestingly, the 66.2 mm recorded in 5 min during this event makes it the world record holder for all-time highest 5-min rainfall, passing the previous world 5-min rainfall record of 63.0 mm in 5 min recorded at Porto Bello, Panama, on 29 November 1911. Return periods of expected maximum daily, hourly and 5-min rainfall, based on yearly highest values, were also calculated for South Africa. This study presents expected maximums for 5-min rainfall in return periods of 10, 25, 50 and 100 years, a first for South Africa, which can inform strategies for disaster risk reduction.

Distribution and redistribution of salt ions in saline soils with shallow groundwater table

V.N. Mathinya — 2024-11-04

Saline water resources are more abundant than freshwater. Bringing these resources into sustainable, productive use will offer opportunities to reduce competition for freshwater resources, especially in arid and semi-arid areas where freshwater is scarce. Hence, the primary objective of this study was to elucidate the dynamics of salt ions in saline profiles of various soil types (sandy Clovelly and sandy loam Bainsvlei) under malt barley cultivation across 2 seasons where no leaching between the seasons took place. Results of this lysimeter study investigating increasing irrigation salinity (ECi ) set at 1.5, 4.5, 6, 9, and 12 dS·m−1 over 2 seasons were used to explore ion dynamics of a saline environment. The lysimeter set-up included a saline constant (1.2 m) groundwater table with its salinity corresponding to ECi . Findings showed that ion concentrations are higher closer to the water source only in the Bainsvlei soil and remain variable in the Clovelly soil. Salt dynamics were more predictable in sandy loam soil than in sandy soil, making management of saline sandy soils far more challenging when leaching is not possible. Therefore, our hypothesis that the absence of leaching between seasons will lead to a differentiated progressive accumulation of salt ions in the soil profile, with variable effects on the soil depending on soil texture, was true. We conclude that the desalinized zone, which we determined to be at a depth of 600 mm, should be used to guide crop selection. Furthermore, in addition to the apparent provision for leaching of saline profiles, fertilization should target restoring ion balances, especially provisioning for calcium deficiencies. Both soils were prone to nutritional disorders, most especially calcium deficiency. Therefore, in addition to provision for leaching saline profiles, fertilization should target calcium provisioning for crop production in arid saline environments.

Fruit growth and water use of two pear cultivars grown in South Africa: implications for precision irrigation scheduling

S. Dzikiti — 2024-11-04

In South Africa, as in other semi-arid countries, sustainable production of high-value crops requires precise management of limited water resources. We investigated daily and seasonal changes in stem and fruit growth as indicators of water stress in pear (Pyrus communis L.) trees, in the Western Cape Province. Stem and fruit growth data were collected hourly throughout the 2022–2023 growing season on 2 cultivars commonly planted in South Africa – Packham’s Triumph and Forelle. Soil water content, tree sap flow, and orchard microclimate were also monitored. Fruit maximum daily shrinkage (MDS) was highly sensitive to soil water deficit and more sensitive than stem size changes. However, the patterns of fruit MDS for both cultivars changed as the season progressed. Early in the season (October–December), there was a strong correlation between fruit MDS and soil water deficit (R2 ~ 0.72). The fruit shrunk with increasing soil water deficit as water loss through transpiration exceeded gains through xylem and phloem inflows. In contrast, daytime fruit size swelled from late December until harvest (February/March), likely because of the dominance of phloem inflows and decreased peel transpiration as the fruit matured. Correlation between fruit expansion and soil water deficit was weaker (R2 ~ 0.32) during the later stage even though fruit growth continued until harvest. Stem MDS consistently showed midday shrinkage throughout the season in response to soil water deficit, but with more scatter (R2 ~ 0.37). Seasonal total transpiration was greater for Forelle (733 mm) than Packham’s Triumph (539 mm) because of the higher leaf area index of the Forelle and the longer growing season. This study suggests that pear fruit growth data can provide accurate estimates of tree water status, but only during the early stages of growth. Towards maturity, fruit size changes respond indirectly to water deficit, possibly through reductions in photosynthesis.

Improving the water quality in the Zandvlei Estuary, Cape Town, by retrofitting sustainable drainage systems in the Diep River catchment

Geordie Thewlis — 2024-11-04

The Zandvlei Estuary is the only functioning estuary along the False Bay coastline of Cape Town and is therefore of extreme local ecological importance. The most significant problems are eutrophication and siltation caused by the increased total inorganic nitrogen (TIN) and soluble ready phosphorus (SRP) levels due to urban development and the associated increased impervious surface area in the catchment that drains into it. In South Africa, stormwater drainage systems conventionally channel everything they collect into receiving water bodies without significant treatment. Sustainable drainage systems (SuDS) provide an alternative approach to managing stormwater runoff. They are designed to manage both stormwater quality and quantity while potentially improving biodiversity and amenity. This project modelled the potential improvement in the quality of the water entering Zandvlei Estuary resulting from the implementation of selected SuDS control measures in Zandvlei’s Diep River catchment using the software program, PCSWMM. SRP, TIN, total phosphorus (TP) and total suspended solids (TSS) were selected as pollutant indicators. Treatment trains that included a large, constructed wetland at the bottom of the catchment will likely provide the greatest improvements to the water quality entering Zandvlei – potentially reducing SRP, TIN, TP and TSS by approximately 59%, 53%, 53%, and 66%, respectively – as well as potentially reducing the runoff by 48%.

Valorisation of acid mine drainage through effective recovery of selected rare earth elements using cationic resins

Nsaka Christophe Ntumba — 2024-11-04

Acid mine drainage (AMD) presents a challenge to the environment if not well managed, but it also presents an opportunity for the recovery of economically valuable products, including rare earth elements (REEs), which are critical for the development of advanced, and green technologies. REE concentrations in AMD samples from coal and gold mines were determined using inductively coupled plasma optical emission spectroscopy (ICP-OES) and their sorption by different cationic resins (CHT4083, CHP4502 and CHP00712) was evaluated. Optimum conditions for the sorption of the REEs by these resins were determined through batch experiments and desorption of the REEs from the resins using different concentrations of sulphuric acid (H2SO4) solutions. Coal mine drainage (CMD), with a low pH of 2.37, had higher amounts of REEs (ΣREE 226.3732 mg/L) than AMD from the gold mines (ΣREE 4.9705 mg/L), with a pH of 3.21. A REE sorption efficiency of up to 98% was obtained with CHP4502 and CHP00712 resins and further optimisation of CHP00712 revealed that a resin volume of 250 mL and a contact time of 10 min were required to successfully remove REEs from 500 mL AMD. The sorption capacities of the resin for the selected REEs were 3.88 mg/g, 0.88 mg/g, 1.37 mg/g, 3.18 mg/g, 0.67 mg/g, 0.01 mg/g and 0.27mg/g for Pr, Gd, Nd, Ce, Sm, Eu and Y, respectively. Elution of the resin with a 0.5 N solution of sulphuric acid desorbed the REEs. AMD from coal mines could be an alternate source of REEs and cationic resins can be used to recover these REEs from the CMD. Further investigations, including impregnation of resin to improve its sorption capacity, and temperature effects on the sorption process, are recommended

Improved photocatalytic degradation of methylene blue by novel hexagonal ZnO particles

Zehra Yigit Avdan — 2024-11-04

Recently, the use of nanoparticles as photocatalysts has gained great importance. However, nanoparticles exhibit some drawbacks for this application and there is a need for new particle technologies to mitigate these drawbacks. A novel particle technology called MicNo based on ZnO has been designed and manufactured, which exhibits the advantages and properties of both micron and nano size. Although performance of MicNo-ZnO has been tested in various applications, it has not been tested as a photocatalyst in any photocatalytic degradation process. In this study, novel designed ZnO was used as a catalyst for methylene blue (MB) degradation in the presence of UV irradiation. The MicNo-ZnO particles were characterized by structural and morphological properties by XRD, BET and SEM analyses. The effects of catalyst amount, pH, temperature and initial concentration on the degradation process were investigated. In addition, a reusability study was carried out with 4 cycles under optimum conditions. The MicNo-ZnO particles showed excellent photocatalytic activity with a degradation rate of 96% for methylene blue in 180 min. The pseudo-first-order rate constant for the photocatalytic degradation of MB by MicNo-ZnO was as high as 0.0236 min−1, confirming that MicNo-ZnO particles can be effectively utilized as an alternative catalyst material.

Yeast-contaminated water as a potential emerging health concern: a review

Tyla Baker — 2024-11-04

Invasive fungal infections pose a serious risk to human health; therefore, it is important to study the dissemination and proliferation of pathogenic fungal species in the environment. This could prove useful in preventing infections in susceptible individuals, such as those who are immune-compromised or suppressed. Pathogenic yeasts belonging to the genera Candida, Cryptococcus and Rhodotorula are commonly found in various water sources that are used for daily activities and are included in the World Health Organization fungal priority pathogens list, further warranting investigation into the possibility that infections may occur through contact with yeast- contaminated water. In addition, the close association between antifungal pollutants and yeast in water may induce acquired antifungal resistance development, further complicating the effective treatment of these infections. Thus, investigating the presence and antifungal susceptibility of yeast found in water and identifying ways to monitor potential fungal pathogens may prove useful in combating invasive fungal infections. This review deals with the occurrence and infection risks posed by pathogenic yeasts in water as well as the possibility of these yeasts acquiring antifungal resistance due to the simultaneous presence of antifungal compounds from medical and agricultural runoff.

Recurrence of cholera epidemics in South Africa: inadequate sanitary facilities, poor environmental monitoring practices, and climate change as possible contributing factors

Pusang King Sekgobela — 2024-11-04

Cholera is an acute infectious disease caused by two toxin-producing strains, namely Vibrio cholerae O1, and Vibrio cholerae O139. Its recorded history stretches as far back as 1817, in Bengal, India, yet it continues to be a public health threat to this present day. Although cholera epidemics are now a relatively rare phenomenon in developed countries, frequent epidemics continue to be experienced in sub- Saharan Africa. Africa accounted for 63.33% of the 223 370 cases of and 4 159 deaths from cholera that were reported globally in 2020. Furthermore, of the 342 900 cholera cases and 3 304 cholera deaths reported globally in 2022, 40.28% of the cases and 77.85% of the deaths were in Africa. Inadequate sanitation infrastructure as well as inadequate provision of quality, safe drinking water in South Africa still creates conducive conditions for the transmission of cholera. In addition, climate change is increasingly becoming a risk factor towards the spread of V. cholerae pathogens in inland regions. To make recommendations on how South Africa, and potentially the Southern African region as a whole, can minimise the resurgence of cholera, this review addressed the following questions: Does South Africa have adequate sanitation infrastructure to curb the spread of cholera? Is there enough intentional surveillance of environmental water sources for vibrios as a cholera outbreak predictive tool? What is the impact of climate change on the resurgence of cholera in South Africa? And, what needs to be done to curb the resurgence of cholera in South Africa?

Innovative Juncus effusus plant biofilter for enhanced ammonia removal: design, construction, and preliminary testing

Tinashe Munhemba — 2024-11-04

A developing trend in stormwater treatment and management is the use of green technologies. Plant biofilters have been gaining increasing use in support of green technology objectives. This technical note reports on the development and preliminary testing of a laboratory-scale plant biofilter prototype for ammonia removal using a South African native plant species (Juncus effusus). The prototype design was based on a conceptual model for nitrogen fixation, plant uptake, bacterial nitrification and soil sorption. Additionally, a plug compartment was incorporated into the design to simulate plug flow as part of the conceptual model. Biofilter models with and without inoculated bacteria were compared. Ammonia reduction, nitrite and nitrate formation were observed. Results showed that the inoculated plant biofilter performed best, with an average of 61% reduction in ammonia within the filter compared to 15% in the normal plant biofilter. The incorporation of a plug compartment aided in slowing down the ammonia infiltration rate, increasing the retention time, and allowing for nitrification to occur.